Diff non-git workspaces via an mtime baseline

`projectBashArtifacts` and `reconcileWorkspaceArtifacts` used to bail
with `not_a_git_repo` whenever the workspace had no `.git`, so bash
output in such workspaces never reached `work_products` and the
DocumentCenter looked empty while files piled up on disk.

`captureWorkspaceBaseline` now walks the workspace at `prepareRun`
time, skipping the same categories the registrability filter rejects
(`.git`, `node_modules`, `.next`, caches) and capping at
`MAX_BASELINE_ENTRIES` so large trees stay bounded. The baseline rides
on `ActiveRunContext.workspaceBaseline` and is passed into every
artifact projection.

`collectChangedPaths` is the single change-detector for both the
per-bash projection and the end-of-run reconciliation. It picks `git
status` when a `.git` is present and falls back to a
`diffAgainstBaseline` walk otherwise. Paths already on the ignore list
still never land in `work_products`; the identity stays
`(company, workspace, provider, externalId)`; the upsert still refreshes
`last_touched_by_run_id` so the deliverable signal follows the latest
touching run.

src/main/agent-runtime/runtime-bridge.ts

@@ -11,7 +11,7 @@ import type { CredentialResolver } from "@main/credentials";
 import { getConnectorDefinition } from "@main/connectors";
 import { projectInboxMessageToPi } from "./inbox-projection";
 import { projectAgentEventToLogChunk, extractTextBody } from "./agent-event-projection";
-import { reconcileWorkspaceArtifacts } from "./artifact-projector";
+import { captureWorkspaceBaseline, reconcileWorkspaceArtifacts } from "./artifact-projector";
 import {
   handleBeforeToolCall,
   handleAfterToolCall,
@@ -130,6 +130,7 @@ export class RuntimeBridge {
         taskId: ctx.taskId,
         workspaceId: ctx.workspaceId,
         workspacePath: ctx.workspacePath,
+        workspaceBaseline: ctx.workspaceBaseline,
       });
       const inserted = outcomes.filter((o) => o.kind === "inserted").length;
       if (inserted > 0) {
@@ -500,6 +501,13 @@ export class RuntimeBridge {
       workspaceId: string | null;
       workspacePath: string | null;
     };
+    // Capture an mtime baseline for non-git workspaces so `bash` and
+    // the end-of-run reconciliation can still diff changed files
+    // against a known-start reference. Git workspaces leave the
+    // baseline as null — `git status` is the source of truth there.
+    const baseline = payload.workspacePath
+      ? captureWorkspaceBaseline(payload.workspacePath)
+      : null;
     this.registerActiveRun({
       runId,
       agentId: payload.agentId,
@@ -510,6 +518,7 @@ export class RuntimeBridge {
       taskSessionId: payload.taskSessionId,
       workspaceId: payload.workspaceId,
       workspacePath: payload.workspacePath,
+      workspaceBaseline: baseline,
       state: "preparing",
     });
     const definition = getConnectorDefinition(payload.connectorId);